<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <button onclick="alert('请先登录!')">弹出警告框</button>
    <button onclick="confirm('确定要删除吗?')">弹出确认框</button>
</body>
<script>
    console.log(parseInt(6.6));
    console.log(parseInt(6.1));
    console.log(parseInt(6));
    console.log(parseInt('6.99'));
    console.log(parseInt('hhh'));

    console.log(parseFloat(6.6));
    console.log(parseFloat(6.1));
    console.log(parseFloat(6));
    console.log(parseFloat('6.99'));
    console.log(parseFloat('hhh'));

    console.log(isNaN('hhh'));
    console.log(isNaN(6.6));
    console.log(isNaN(6));
    console.log(isNaN('6'));


</script>
</html>